For example, JP 2003-049849 A discloses a work spindle of a machine tool in which the spindle shaft is supported via ball bearings in an outside housing. In this connection, in the outside housing there is a grease reservoir for lubricating the ball bearings, the grease reservoir being closed on one side with a movable piston which is moved by compressed air or another pressurized gas for delivery of grease in the direction of the ball bearings.
The object of the invention is to devise an improved device of the initially mentioned type so that among others extremely small amounts of grease can be delivered in an exactly controllable manner from the grease reservoir to the antifriction bearing.